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Li WW, Zhao Y, Liu HC, Liu J, Chan SO, Zhong YF, Zhang TY, Liu Y, Zhang W, Xia YQ, Chi XC, Xu J, Wang Y, Wang J. Roles of Thermosensitive Transient Receptor Channels TRPV1 and TRPM8 in Paclitaxel-Induced Peripheral Neuropathic Pain. Int J Mol Sci 2024; 25:5813. [PMID: 38892000 PMCID: PMC11171746 DOI: 10.3390/ijms25115813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 05/20/2024] [Accepted: 05/23/2024] [Indexed: 06/21/2024] Open
Abstract
Paclitaxel, a microtubule-stabilizing chemotherapy drug, can cause severe paclitaxel-induced peripheral neuropathic pain (PIPNP). The roles of transient receptor potential (TRP) ion channel vanilloid 1 (TRPV1, a nociceptor and heat sensor) and melastatin 8 (TRPM8, a cold sensor) in PIPNP remain controversial. In this study, Western blotting, immunofluorescence staining, and calcium imaging revealed that the expression and functional activity of TRPV1 were upregulated in rat dorsal root ganglion (DRG) neurons in PIPNP. Behavioral assessments using the von Frey and brush tests demonstrated that mechanical hyperalgesia in PIPNP was significantly inhibited by intraperitoneal or intrathecal administration of the TRPV1 antagonist capsazepine, indicating that TRPV1 played a key role in PIPNP. Conversely, the expression of TRPM8 protein decreased and its channel activity was reduced in DRG neurons. Furthermore, activation of TRPM8 via topical application of menthol or intrathecal injection of WS-12 attenuated the mechanical pain. Mechanistically, the TRPV1 activity triggered by capsaicin (a TRPV1 agonist) was reduced after menthol application in cultured DRG neurons, especially in the paclitaxel-treated group. These findings showed that upregulation of TRPV1 and inhibition of TRPM8 are involved in the generation of PIPNP, and they suggested that inhibition of TRPV1 function in DRG neurons via activation of TRPM8 might underlie the analgesic effects of menthol.
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Affiliation(s)
- Wen-Wen Li
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Yan Zhao
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Huai-Cun Liu
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Jiao Liu
- Center of Medical and Health Analysis, Peking University Health Science Center, Beijing 100191, China;
| | - Sun-On Chan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Yi-Fei Zhong
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Tang-Yu Zhang
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Yu Liu
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Wei Zhang
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Yu-Qi Xia
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Xiao-Chun Chi
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Jian Xu
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
| | - Yun Wang
- Neuroscience Research Institute and Department of Neurobiology, Key Laboratory for Neuroscience of Ministry of Education and Neuroscience, Peking University Health Science Center, Beijing 100191, China
- PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Jun Wang
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; (W.-W.L.); (Y.Z.); (H.-C.L.); (Y.-F.Z.); (T.-Y.Z.); (Y.L.); (W.Z.); (Y.-Q.X.); (X.-C.C.); (J.X.)
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Ricci S, Kim MS, Simons CT. The impact of temperature and a chemesthetic cooling agent on lingual roughness sensitivity. Chem Senses 2024; 49:bjae013. [PMID: 38526180 DOI: 10.1093/chemse/bjae013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Indexed: 03/26/2024] Open
Abstract
Oral tactile sensitivity underpins food texture perception, but few studies have investigated mechanoreception in oral tissues. During food consumption, oral tissues are exposed to a wide range of temperatures and chemical entities. The objective of the present study was to assess the influence of thermal sensations on lingual roughness sensitivity. Just-noticeable difference thresholds (JNDs) were determined using the staircase method for surface roughness from stainless steel coupons (Ra; 0.177-0.465 µm). Thresholds were assessed when cooling or heating the metal stimuli (n = 32 subjects). Compared to the JND threshold obtained at an ambient stimulus temperature (21 °C: 0.055 ± 0.010 μm), a cold (8 °C) temperature significantly (P = 0.019) reduced tongue sensitivity (i.e. increased JND) to surface roughness (0.109 ± 0.016 μm, respectively) whereas warm and hot temperatures had no significant effect (35 °C: 0.084 ± 0.012 μm; 45 °C: 0.081 ± 0.011 μm). To assess whether the effect of cooling on roughness thresholds is TRPM8-dependent, we collected roughness thresholds in a second cohort of subjects (n = 27) following the lingual application of the cooling compound Evercool 190 (24.3 µM). Interestingly, when Evercool 190 was used to elicit the cold sensation, lingual roughness JNDs were unaffected compared to the control application of water (EC: 0.112 ± 0.016 μm; water: 0.102 ± 0.017 μm; P = 0.604). That lingual roughness sensitivity is decreased by cold temperature, but not chemicals evoking cold sensations, suggests the mechanism underpinning thermal modulation is not TRPM8 dependent.
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Affiliation(s)
- Sebastiano Ricci
- Department of Food Science & Technology, The Ohio State University, 2015 Fyffe Rd., Columbus, OH 43210-1007, United States
- Department of Food Science, University of Parma, Science Area Park, 27/ A, 43124 Parma, Italy
| | - Min Sung Kim
- Department of Food Science & Technology, The Ohio State University, 2015 Fyffe Rd., Columbus, OH 43210-1007, United States
| | - Christopher T Simons
- Department of Food Science & Technology, The Ohio State University, 2015 Fyffe Rd., Columbus, OH 43210-1007, United States
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Lee S, Jang IS. Menthol excites dural afferent neurons by inhibiting leak K + conductance in rats. Neurosci Lett 2023; 813:137427. [PMID: 37549867 DOI: 10.1016/j.neulet.2023.137427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 08/02/2023] [Accepted: 08/03/2023] [Indexed: 08/09/2023]
Abstract
Menthol-a natural organic compound-is widely used for relieving various pain conditions including migraine. However, a high dose of menthol reportedly decreases pain thresholds and enhances pain responses. Accordingly, in the present study, we addressed the effect of menthol on the excitability of acutely isolated dural afferent neurons, which were identified with a fluorescent dye, using the whole-cell patch-clamp technique. Under a voltage-clamped condition, menthol altered the holding current levels in a concentration-dependent manner. The menthol-induced current (IMenthol) remained unaffected by the addition of selective transient receptor potential melastatin 8 antagonists. Moreover, the reversal potential of IMenthol was similar to the equilibrium potential of K+. IMenthol was accompanied by an increase in input resistance, thereby suggesting that menthol decreases the leak K+ conductance. Under a current-clamped condition, menthol caused depolarization of the membrane potential and decreased the threshold for the generation of action potential. While the IMenthol was substantially inhibited by 10 μM XE-991, a selective KV7 blocker, the M-current mediated by KV7 was not detected in the nociceptive neurons tested in the present study. Moreover, IMenthol decreased under acidic extracellular pH conditions or in the presence of 3 μM A-1899, a selective K2P3.1 and K2P9.1 blocker. The present results suggest that menthol inhibits leak K+ channels, possibly acid-sensitive two-pore domain K+ channels, thereby increasing the excitability of nociceptive sensory neurons. The resultant increase in neuron excitability may partially be responsible for the pronociceptive effect mediated by high menthol doses.
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Affiliation(s)
- Seungbo Lee
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 41940, Republic of Korea.
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Lötsch J, Mayer B, Kringel D. Machine learning analysis predicts a person's sex based on mechanical but not thermal pain thresholds. Sci Rep 2023; 13:7332. [PMID: 37147321 PMCID: PMC10163041 DOI: 10.1038/s41598-023-33337-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/11/2023] [Indexed: 05/07/2023] Open
Abstract
Sex differences in pain perception have been extensively studied, but precision medicine applications such as sex-specific pain pharmacology have barely progressed beyond proof-of-concept. A data set of pain thresholds to mechanical (blunt and punctate pressure) and thermal (heat and cold) stimuli applied to non-sensitized and sensitized (capsaicin, menthol) forearm skin of 69 male and 56 female healthy volunteers was analyzed for data structures contingent with the prior sex structure using unsupervised and supervised approaches. A working hypothesis that the relevance of sex differences could be approached via reversibility of the association, i.e., sex should be identifiable from pain thresholds, was verified with trained machine learning algorithms that could infer a person's sex in a 20% validation sample not seen to the algorithms during training, with balanced accuracy of up to 79%. This was only possible with thresholds for mechanical stimuli, but not for thermal stimuli or sensitization responses, which were not sufficient to train an algorithm that could assign sex better than by guessing or when trained with nonsense (permuted) information. This enabled the translation to the molecular level of nociceptive targets that convert mechanical but not thermal information into signals interpreted as pain, which could eventually be used for pharmacological precision medicine approaches to pain. By exploiting a key feature of machine learning, which allows for the recognition of data structures and the reduction of information to the minimum relevant, experimental human pain data could be characterized in a way that incorporates "non" logic that could be translated directly to the molecular pharmacological level, pointing toward sex-specific precision medicine for pain.
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Affiliation(s)
- Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany.
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Theodor-Stern-Kai 7, 60596, Frankfurt, Germany.
| | - Benjamin Mayer
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
| | - Dario Kringel
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
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Li Z, Zhang H, Wang Y, Li Y, Li Q, Zhang L. The distinctive role of menthol in pain and analgesia: Mechanisms, practices, and advances. Front Mol Neurosci 2022; 15:1006908. [PMID: 36277488 PMCID: PMC9580369 DOI: 10.3389/fnmol.2022.1006908] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/13/2022] [Indexed: 11/13/2022] Open
Abstract
Menthol is an important flavoring additive that triggers a cooling sensation. Under physiological condition, low to moderate concentrations of menthol activate transient receptor potential cation channel subfamily M member 8 (TRPM8) in the primary nociceptors, such as dorsal root ganglion (DRG) and trigeminal ganglion, generating a cooling sensation, whereas menthol at higher concentration could induce cold allodynia, and cold hyperalgesia mediated by TRPM8 sensitization. In addition, the paradoxical irritating properties of high concentrations of menthol is associated with its activation of transient receptor potential cation channel subfamily A member 1 (TRPA1). Under pathological situation, menthol activates TRPM8 to attenuate mechanical allodynia and thermal hyperalgesia following nerve injury or chemical stimuli. Recent reports have recapitulated the requirement of central group II/III metabotropic glutamate receptors (mGluR) with endogenous κ-opioid signaling pathways for menthol analgesia. Additionally, blockage of sodium channels and calcium influx is a determinant step after menthol exposure, suggesting the possibility of menthol for pain management. In this review, we will also discuss and summarize the advances in menthol-related drugs for pathological pain treatment in clinical trials, especially in neuropathic pain, musculoskeletal pain, cancer pain and postoperative pain, with the aim to find the promising therapeutic candidates for the resolution of pain to better manage patients with pain in clinics.
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Affiliation(s)
- Ziping Li
- The Graduate School, Tianjin Medical University, Tianjin, China
| | - Haoyue Zhang
- The Graduate School, Tianjin Medical University, Tianjin, China
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yigang Wang
- The Graduate School, Tianjin Medical University, Tianjin, China
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yize Li
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Qing Li
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
- Qing Li,
| | - Linlin Zhang
- Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
- *Correspondence: Linlin Zhang,
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O'Hara DJ, Tyler TF, McHugh MP, Kwiecien SY, Bergeron T. Use of a Non-Pharmacological Pain Relief Kit to Reduce Opioid Use Following Orthopedic Surgery: A Prospective Randomized Study. Int J Sports Phys Ther 2022; 17:915-923. [PMID: 35949389 PMCID: PMC9340831 DOI: 10.26603/001c.36625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 03/24/2022] [Indexed: 11/18/2022] Open
Abstract
Introduction Opioid prescription to treat pain among orthopedic surgery patients remains common practice in the United States but overprescribing opioids can lead to abuse. The purpose of this study was to determine the effect of a multimodal non-pharmacological 'pain relief kit' on pain, function, and opioid consumption in individuals recovering from orthopedic surgery. Hypothesis Patients provided with the pain relief kit would consume less opioid medication, report lower pain levels, and have better functional outcome scores than the control group. Level of Evidence 2b. Methods Fifty-three subjects (18 women, 35 men) having orthopedic surgery were randomly assigned to either receive the Pain Relief Kit (treatment) or control group. At the first postoperative physical therapy visit (within 1 week of surgery) the treatment group was provided elastic resistance bands, kinesiology tape, Biofreeze, and a hot/cold pack as part of the Pain Relief Kit. Patients completed the SF-36 and either the DASH or LEFS questionnaires consistent with their surgery at baseline and four weeks post-op. Both groups reported daily pain (Visual Analogue Scale), opioid use, and over the counter medication use. The treatment group also recorded daily kit modality use. Results There was no significant difference in total opioid use between the treatment (108±252 milligram morphine equivalents) and control groups (132±158 MME; p=0.696). Opioid use and pain declined from week one to four with no difference between groups (p<0.001). Outcome scores and SF-36 scores improved from week one to four with no difference between groups (p<0.001). Conclusion A non-pharmacological pain relief kit did not have an effect on opioid use in this patient population nor did it improve pain relief or function compared to controls.
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Saltarella I, Altamura C, Lamanuzzi A, Apollonio B, Vacca A, Frassanito MA, Desaphy JF. Ion Channels in Multiple Myeloma: Pathogenic Role and Therapeutic Perspectives. Int J Mol Sci 2022; 23:ijms23137302. [PMID: 35806308 PMCID: PMC9266328 DOI: 10.3390/ijms23137302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 06/27/2022] [Accepted: 06/27/2022] [Indexed: 12/10/2022] Open
Abstract
Ion channels are pore-forming proteins that allow ions to flow across plasma membranes and intracellular organelles in both excitable and non-excitable cells. They are involved in the regulation of several biological processes (i.e., proliferation, cell volume and shape, differentiation, migration, and apoptosis). Recently, the aberrant expression of ion channels has emerged as an important step of malignant transformation, tumor progression, and drug resistance, leading to the idea of “onco-channelopathy”. Here, we review the contribution of ion channels and transporters in multiple myeloma (MM), a hematological neoplasia characterized by the expansion of tumor plasma cells (MM cells) in the bone marrow (BM). Deregulation of ion channels sustains MM progression by modulating intracellular pathways that promote MM cells’ survival, proliferation, and drug resistance. Finally, we focus on the promising role of ion channels as therapeutic targets for the treatment of MM patients in a combination strategy with currently used anti-MM drugs to improve their cytotoxic activity and reduce adverse effects.
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Affiliation(s)
- Ilaria Saltarella
- Department of Biomedical Sciences and Human Oncology, Section of Pharmacology, University of Bari Aldo Moro Medical School, Piazza Giulio Cesare 11, I-70124 Bari, Italy
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, Section of Pharmacology, University of Bari Aldo Moro Medical School, Piazza Giulio Cesare 11, I-70124 Bari, Italy
| | - Aurelia Lamanuzzi
- Department of Biomedical Sciences and Human Oncology, Section of Internal Medicine, University of Bari Aldo Moro Medical School, I-70124 Bari, Italy
| | - Benedetta Apollonio
- Department of Biomedical Sciences and Human Oncology, Section of Internal Medicine, University of Bari Aldo Moro Medical School, I-70124 Bari, Italy
| | - Angelo Vacca
- Department of Biomedical Sciences and Human Oncology, Section of Internal Medicine, University of Bari Aldo Moro Medical School, I-70124 Bari, Italy
| | - Maria Antonia Frassanito
- Department of Biomedical Sciences and Human Oncology, Section of General Pathology, University of Bari Aldo Moro Medical School, I-70124 Bari, Italy
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, Section of Pharmacology, University of Bari Aldo Moro Medical School, Piazza Giulio Cesare 11, I-70124 Bari, Italy
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Jackson A, Green B, Erythropel HC, Kong G, Cavallo DA, Eid T, Gueorguieva R, Buta E, O’Malley SS, Krishnan-Sarin S. Influence of menthol and green apple e-liquids containing different nicotine concentrations among youth e-cigarette users. Exp Clin Psychopharmacol 2021; 29:355-365. [PMID: 32297782 PMCID: PMC7572568 DOI: 10.1037/pha0000368] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
E-cigarettes are popular among adolescents. Given that flavors enhance e-cigarette appeal, this study examined the influence of flavors on nicotine in e-cigarettes. Youth e-cigarette users (average 26.2 days [SD = 3.6] in past 28 days) were randomized to use e-cigarettes containing 6 or 12 mg/mL of freebase nicotine and completed 4 test sessions. During the first 3 test sessions, participants completed 3 fixed puffing bouts (1 puffing bout = 10 puffs, 3 s each, 30-s interval), using menthol, green-apple, and unflavored e-liquids (50 propylene glycol [PG]/50 vegetable glycerin [VG]) with their assigned nicotine concentration in a random order using a ∼5.5-W V2 e-cigarette device. After each puffing bout, participants assessed subjective effects of nicotine and flavor. In the 4th test session, participants used any of the e-liquids they had tried in the earlier sessions, ad libitum for 60 min and the amount of e-liquid used for each flavor and the number of puffs was assessed. Participants (n = 49; 6 mg/mL [n = 24]; 12 mg/mL [n = 25]) were 63.3% male, 65.3% non-Hispanic White with an average age of 18.7 (SD = 0.9). Mixed models analysis revealed that green apple and 6 mg/mL of nicotine independently increased liking of e-cigarette taste. In addition, green apple produced higher ratings of fruitiness, sourness, sweetness, and menthol produced higher ratings of coolness. We did not observe any interactions between nicotine and flavor. Youth liked the taste of e-liquids containing green-apple flavor or low nicotine concentration which highlights the appeal of fruit flavors in e-cigarettes to adolescents. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
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Affiliation(s)
- Asti Jackson
- Department of Psychiatry, Yale School of Medicine
| | - Barry Green
- The John B. Pierce Laboratory and Department of Surgery, Yale School of Medicine
| | | | - Grace Kong
- Department of Psychiatry, Yale School of Medicine
| | | | - Tore Eid
- Department of Laboratory Medicine, Yale School of Medicine
| | | | - Eugenia Buta
- Department of Biostatistics, Yale School of Public Health
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Quesada C, Kostenko A, Ho I, Leone C, Nochi Z, Stouffs A, Wittayer M, Caspani O, Brix Finnerup N, Mouraux A, Pickering G, Tracey I, Truini A, Treede RD, Garcia-Larrea L. Human surrogate models of central sensitization: A critical review and practical guide. Eur J Pain 2021; 25:1389-1428. [PMID: 33759294 PMCID: PMC8360051 DOI: 10.1002/ejp.1768] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 03/17/2021] [Accepted: 03/21/2021] [Indexed: 12/11/2022]
Abstract
Background As in other fields of medicine, development of new medications for management of neuropathic pain has been difficult since preclinical rodent models do not necessarily translate to the clinics. Aside from ongoing pain with burning or shock‐like qualities, neuropathic pain is often characterized by pain hypersensitivity (hyperalgesia and allodynia), most often towards mechanical stimuli, reflecting sensitization of neural transmission. Data treatment We therefore performed a systematic literature review (PubMed‐Medline, Cochrane, WoS, ClinicalTrials) and semi‐quantitative meta‐analysis of human pain models that aim to induce central sensitization, and generate hyperalgesia surrounding a real or simulated injury. Results From an initial set of 1569 reports, we identified and analysed 269 studies using more than a dozen human models of sensitization. Five of these models (intradermal or topical capsaicin, low‐ or high‐frequency electrical stimulation, thermode‐induced heat‐injury) were found to reliably induce secondary hyperalgesia to pinprick and have been implemented in multiple laboratories. The ability of these models to induce dynamic mechanical allodynia was however substantially lower. The proportion of subjects who developed hypersensitivity was rarely provided, giving rise to significant reporting bias. In four of these models pharmacological profiles allowed to verify similarity to some clinical conditions, and therefore may inform basic research for new drug development. Conclusions While there is no single “optimal” model of central sensitization, the range of validated and easy‐to‐use procedures in humans should be able to inform preclinical researchers on helpful potential biomarkers, thereby narrowing the translation gap between basic and clinical data. Significance Being able to mimic aspects of pathological pain directly in humans has a huge potential to understand pathophysiology and provide animal research with translatable biomarkers for drug development. One group of human surrogate models has proven to have excellent predictive validity: they respond to clinically active medications and do not respond to clinically inactive medications, including some that worked in animals but failed in the clinics. They should therefore inform basic research for new drug development.
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Affiliation(s)
- Charles Quesada
- NeuroPain lab, Lyon Centre for Neuroscience Inserm U1028, Lyon, France.,Pain Center Neurological Hospital (CETD), Hospices Civils de Lyon, Lyon, France
| | - Anna Kostenko
- Department of Neurophysiology, Mannheim center for Translational Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Idy Ho
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Caterina Leone
- Department of Human Neuroscience, Sapienza University, Rome, Italy
| | - Zahra Nochi
- Danish Pain Research Center, Dept of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Alexandre Stouffs
- Institute of Neuroscience (IoNS), Université Catholique de Louvain (UCLouvain), Ottignies-Louvain-la-Neuve, Belgium
| | - Matthias Wittayer
- Department of Neurophysiology, Mannheim center for Translational Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Ombretta Caspani
- Department of Neurophysiology, Mannheim center for Translational Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Nanna Brix Finnerup
- Danish Pain Research Center, Dept of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - André Mouraux
- Institute of Neuroscience (IoNS), Université Catholique de Louvain (UCLouvain), Ottignies-Louvain-la-Neuve, Belgium
| | | | - Irene Tracey
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Andrea Truini
- Department of Human Neuroscience, Sapienza University, Rome, Italy
| | - Rolf-Detlef Treede
- Department of Neurophysiology, Mannheim center for Translational Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Luis Garcia-Larrea
- NeuroPain lab, Lyon Centre for Neuroscience Inserm U1028, Lyon, France.,Pain Center Neurological Hospital (CETD), Hospices Civils de Lyon, Lyon, France
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Topical Treatments and Their Molecular/Cellular Mechanisms in Patients with Peripheral Neuropathic Pain-Narrative Review. Pharmaceutics 2021; 13:pharmaceutics13040450. [PMID: 33810493 PMCID: PMC8067282 DOI: 10.3390/pharmaceutics13040450] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/17/2021] [Accepted: 03/22/2021] [Indexed: 12/25/2022] Open
Abstract
Neuropathic pain in humans results from an injury or disease of the somatosensory nervous system at the peripheral or central level. Despite the considerable progress in pain management methods made to date, peripheral neuropathic pain significantly impacts patients' quality of life, as pharmacological and non-pharmacological methods often fail or induce side effects. Topical treatments are gaining popularity in the management of peripheral neuropathic pain, due to excellent safety profiles and preferences. Moreover, topical treatments applied locally may target the underlying mechanisms of peripheral sensitization and pain. Recent studies showed that peripheral sensitization results from interactions between neuronal and non-neuronal cells, with numerous signaling molecules and molecular/cellular targets involved. This narrative review discusses the molecular/cellular mechanisms of drugs available in topical formulations utilized in clinical practice and their effectiveness in clinical studies in patients with peripheral neuropathic pain. We searched PubMed for papers published from 1 January 1995 to 30 November 2020. The key search phrases for identifying potentially relevant articles were "topical AND pain", "topical AND neuropathic", "topical AND treatment", "topical AND mechanism", "peripheral neuropathic", and "mechanism". The result of our search was 23 randomized controlled trials (RCT), 9 open-label studies, 16 retrospective studies, 20 case (series) reports, 8 systematic reviews, 66 narrative reviews, and 140 experimental studies. The data from preclinical studies revealed that active compounds of topical treatments exert multiple mechanisms of action, directly or indirectly modulating ion channels, receptors, proteins, and enzymes expressed by neuronal and non-neuronal cells, and thus contributing to antinociception. However, which mechanisms and the extent to which the mechanisms contribute to pain relief observed in humans remain unclear. The evidence from RCTs and reviews supports 5% lidocaine patches, 8% capsaicin patches, and botulinum toxin A injections as effective treatments in patients with peripheral neuropathic pain. In turn, single RCTs support evidence of doxepin, funapide, diclofenac, baclofen, clonidine, loperamide, and cannabidiol in neuropathic pain states. Topical administration of phenytoin, ambroxol, and prazosin is supported by observational clinical studies. For topical amitriptyline, menthol, and gabapentin, evidence comes from case reports and case series. For topical ketamine and baclofen, data supporting their effectiveness are provided by both single RCTs and case series. The discussed data from clinical studies and observations support the usefulness of topical treatments in neuropathic pain management. This review may help clinicians in making decisions regarding whether and which topical treatment may be a beneficial option, particularly in frail patients not tolerating systemic pharmacotherapy.
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Fakih D, Baudouin C, Réaux-Le Goazigo A, Mélik Parsadaniantz S. TRPM8: A Therapeutic Target for Neuroinflammatory Symptoms Induced by Severe Dry Eye Disease. Int J Mol Sci 2020; 21:E8756. [PMID: 33228217 PMCID: PMC7699525 DOI: 10.3390/ijms21228756] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/06/2020] [Accepted: 11/17/2020] [Indexed: 12/23/2022] Open
Abstract
Dry eye disease (DED) is commonly associated with ocular surface inflammation and pain. In this study, we evaluated the effectiveness of repeated instillations of transient receptor potential melastatin 8 (TRPM8) ion channel antagonist M8-B on a mouse model of severe DED induced by the excision of extra-orbital lacrimal and Harderian glands. M8-B was topically administered twice a day from day 7 until day 21 after surgery. Cold and mechanical corneal sensitivities and spontaneous ocular pain were monitored at day 21. Ongoing and cold-evoked ciliary nerve activities were next evaluated by electrophysiological multi-unit extracellular recording. Corneal inflammation and expression of genes related to neuropathic pain and inflammation were assessed in the trigeminal ganglion. We found that DED mice developed a cold allodynia consistent with higher TRPM8 mRNA expression in the trigeminal ganglion (TG). Chronic M8-B instillations markedly reversed both the corneal mechanical allodynia and spontaneous ocular pain commonly associated with persistent DED. M8-B instillations also diminished the sustained spontaneous and cold-evoked ciliary nerve activities observed in DED mice as well as inflammation in the cornea and TG. Overall, our study provides new insight into the effectiveness of TRPM8 blockade for alleviating corneal pain syndrome associated with severe DED, opening a new avenue for ocular pain management.
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Affiliation(s)
- Darine Fakih
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France; (D.F.); (C.B.); (A.R.-L.G.)
- R&D Department, Laboratoires Théa, 12 rue Louis Biérot, F-63000 Clermont-Ferrand, France
| | - Christophe Baudouin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France; (D.F.); (C.B.); (A.R.-L.G.)
- CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, 17 rue Moreau, F-75012 Paris, France
- Department of Ophthalmology, Ambroise Paré Hospital, AP-HP, University of Versailles Saint-Quentin-en-Yvelines, 9 avenue Charles de Gaulle, F-92100 Boulogne-Billancourt, France
| | - Annabelle Réaux-Le Goazigo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France; (D.F.); (C.B.); (A.R.-L.G.)
| | - Stéphane Mélik Parsadaniantz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France; (D.F.); (C.B.); (A.R.-L.G.)
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Choi IS, Cho JH, Nakamura M, Jang IS. Menthol facilitates excitatory and inhibitory synaptic transmission in rat medullary dorsal horn neurons. Brain Res 2020; 1750:147149. [PMID: 33035497 DOI: 10.1016/j.brainres.2020.147149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 09/14/2020] [Accepted: 10/02/2020] [Indexed: 10/23/2022]
Abstract
Menthol, which acts as an agonist for transient receptor potential melastatin 8 (TRPM8), has complex effects on nociceptive transmission, including pain relief and hyperalgesia. Here, we addressed the effects of menthol on spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs, respectively) in medullary dorsal horn neurons, using a whole-cell patch-clamp technique. Menthol significantly increased sEPSC frequency, in a concentration-dependent manner, without affecting current amplitudes. The menthol-induced increase in sEPSC frequency could be completely blocked by AMTB, a TRPM8 antagonist, but was not blocked by HC-030031, a transient receptor potential ankyrin 1 (TRPA1) antagonist. Menthol still increased sEPSC frequency in the presence of Cd2+, a general voltage-gated Ca2+ channel blocker, suggesting that voltage-gated Ca2+ channels are not involved in the menthol-induced increase in sEPSC frequency. However, menthol failed to increase sEPSC frequency in the absence of extracellular Ca2+, suggesting that TRPM8 on primary afferent terminals is Ca2+ permeable. On the other hand, menthol also increased sIPSC frequency, without affecting current amplitudes. The menthol-induced increase in sIPSC frequency could be completely blocked by either AMTB or CNQX, an AMPA/KA receptor antagonist, suggesting that the indirect increase in excitability of inhibitory interneurons may lead to the facilitation of spontaneous GABA and/or glycine release. The present results suggested that menthol exerts analgesic effects, via the enhancement of inhibitory synaptic transmission, through central feed-forward neural circuits within the medullary dorsal horn region.
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Affiliation(s)
- In-Sun Choi
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea
| | - Jin-Hwa Cho
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea
| | - Michiko Nakamura
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 41940, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, Daegu 41940, Republic of Korea.
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Khaleel R, Tremblay F. Modulation of the cutaneous and cortical silent period in response to local menthol application. Somatosens Mot Res 2020; 37:277-283. [PMID: 32873145 DOI: 10.1080/08990220.2020.1815691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In this study, we investigated the effects of menthol application on the cortical and cutaneous silent period (CSP/cutSP). Both the cutSP and CSP were assessed while participants (n = 11, young adults) exerted a light contraction with the right thumb. In the 1st block of trials, SPs were measured after the application of a Neutral gel (Aloe Vera) to the dorsal aspect of the hand. In the 2nd block, the same measures were repeated following a Menthol gel (4%) application. Subjective ratings of cooling sensations were obtained for each block. The Neutral gel was consistently perceived as slightly cool by participants, wheres the Menthol gel elicited sensations from cool to very cold. Paired t-tests showed no difference in the cutSP duration between the two conditions, whereas a significant increase in the CSP was detected with the Menthol condition. No correlation was found between changes in the CSP and those of the cutSP. These results highlight the difference between the cutSP and the CSP, as inhibitory phenomena, and point to a cortical contribution to the soothing effects associated with topical menthol applications.
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Affiliation(s)
| | - François Tremblay
- Bruyère Research Institute, Ottawa, Ontario, Canada.,School of Rehabilitation Sciences, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
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Bagdas D, Jackson A, Carper M, Chen RYT, Akinola LS, Damaj MI. Impact of menthol on nicotine intake and preference in mice: Concentration, sex, and age differences. Neuropharmacology 2020; 179:108274. [PMID: 32827516 DOI: 10.1016/j.neuropharm.2020.108274] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 08/09/2020] [Accepted: 08/11/2020] [Indexed: 12/13/2022]
Abstract
Menthol has been shown to contribute to the appeal of tobacco products in humans. However, factors such as sex, age and menthol concentration remain unclear in the interaction between menthol and nicotine. To understand these factors, we utilized a mouse model to determine the impact of menthol on oral nicotine consumption. A range of menthol concentrations (oral and systemic) were tested with or without oral nicotine using the two-bottle choice paradigm in adolescent and adult female and male C57BL/6J mice. Moreover, genetically modified mice were used to investigate the role of α7 nicotinic acetylcholine receptors (nAChRs) on the effects of menthol. Menthol addition to nicotine solution increased oral nicotine consumption in C57BL/6J mice in a sex- and menthol concentration-dependent manner. At lower menthol concentrations, female mice demonstrated an enhancement of nicotine consumption and male mice showed a similar behavior at higher menthol concentrations. Menthol drinking alone was only significantly different by sex at 60 μg/ml menthol concentration where female mice had higher menthol intake than males. Menthol administered both orally and systemically (intraperitoneal) increased oral nicotine consumption. Adolescent female mice had a higher nicotine intake at lower menthol concentrations compared to their adult counterparts. While α7 nAChR wild type mice consumed more mentholated nicotine solution than nicotine only solution, this effect was abolished in KO mice. Effects of menthol are concentration-, sex-, age-, and α7 nAChR-dependent. Oral and intraperitoneal menthol increases nicotine intake, suggesting that sensory, peripheral, and/or central mechanisms are involved in effects of menthol on oral nicotine consumption.
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Affiliation(s)
- Deniz Bagdas
- Department of Psychiatry, School of Medicine, Yale University, New Haven, CT, USA; Yale Tobacco Center of Regulatory Science, Yale University, New Haven, CT, USA; The Center for the Study for Tobacco Products, Virginia Commonwealth University, Richmond, VA, USA.
| | - Asti Jackson
- Department of Psychiatry, School of Medicine, Yale University, New Haven, CT, USA; Yale Tobacco Center of Regulatory Science, Yale University, New Haven, CT, USA
| | - Moriah Carper
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA
| | - Rita Yu-Tzu Chen
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA
| | - Lois S Akinola
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA; The Center for the Study for Tobacco Products, Virginia Commonwealth University, Richmond, VA, USA
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Forstenpointner J, Binder A, Maag R, Granert O, Hüllemann P, Peller M, Wasner G, Wolff S, Jansen O, Siebner HR, Baron R. Neuroimaging Of Cold Allodynia Reveals A Central Disinhibition Mechanism Of Pain. J Pain Res 2019; 12:3055-3066. [PMID: 31807061 PMCID: PMC6857664 DOI: 10.2147/jpr.s216508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/12/2019] [Indexed: 12/19/2022] Open
Abstract
Purpose Allodynia refers to pain evoked by physiologically innocuous stimuli. It is a disabling symptom of neuropathic pain following a lesion within the peripheral or central nervous system. In fact, two different pathophysiological mechanisms of cold allodynia (ie, hypersensitivity to innocuous cold) have been proposed. The peripheral sensitization of nociceptive neurons can produce cold allodynia, which can be induced experimentally by a topical application of menthol. An alternative mechanism involves reduced inhibition of central pain processing by innocuous cold stimuli. A model to induce the latter type of allodynia is the conduction block of peripheral A-fiber input. Patients and methods In the presented study, functional MRI was used to analyze these two different experimental models of cold allodynia. In order to identify the underlying cerebral activation patterns of both mechanisms, the application of menthol and the induction of a mechanical A-fiber blockade were studied in healthy volunteers. Results The block-induced cold allodynia caused significantly stronger activation of the medial polymodal pain processing pathway, including left medial thalamus, anterior cingulate cortex, and medial prefrontal cortex. In contrast, menthol-induced cold allodynia caused significantly stronger activity of the left lateral thalamus as well as the primary and secondary somatosensory cortices, key structures of the lateral discriminative pathway of pain processing. Mean pain intensity did not differ between both forms of cold allodynia. Conclusion Experimental cold allodynia is mediated in different cerebral areas depending on the underlying pathophysiology. The activity pattern associated with block-induced allodynia confirms a fundamental integration between painful and non-painful temperature sensation, ie, the cold-induced inhibition of cold pain.
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Affiliation(s)
- Julia Forstenpointner
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.,Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Andreas Binder
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.,Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Rainer Maag
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.,Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Oliver Granert
- Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Philipp Hüllemann
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.,Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Martin Peller
- Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Gunnar Wasner
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.,Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Stefan Wolff
- Institute of Radiology and Neuroradiology, University Hospital of Schleswig-Holstein, Kiel, Germany
| | - Olav Jansen
- Institute of Radiology and Neuroradiology, University Hospital of Schleswig-Holstein, Kiel, Germany
| | - Hartwig Roman Siebner
- Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.,Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.,Department of Neurology, Copenhagen University Hospital Bispebjerg, Description, Copenhagen, Denmark.,Institute for Clinical Medicine, Faculty of Health and Clinical Sciences, University of Copenhagen, Description, Copenhagen, Denmark
| | - Ralf Baron
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.,Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany
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Wright A, Benson HAE, Moss P. Development of a topical menthol stimulus to evaluate cold hyperalgesia. Musculoskelet Sci Pract 2019; 41:55-63. [PMID: 31010570 DOI: 10.1016/j.msksp.2019.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 11/25/2022]
Abstract
PURPOSE Cold hyperalgesia is an indicator of widespread pain sensitivity and is associated with poor clinical outcomes. Menthol activates TRPM8, a cold-sensing receptor channel. This research evaluated topical menthol as a potential stimulus to be used in the clinical evaluation of cold hyperalgesia. METHODS Participants were 59 pain free volunteers (17 male: 42 female). A blinded, repeated measures design was used. Participants received applications of menthol at different concentrations in a liquid (study 1) or gel (study 2) formulation with a 24-h interval between each application. Each menthol concentration was applied for 15 min and participants were asked to rate the sensation produced using a series of visual analogue scales and by selecting words from a descriptor list derived from the McGill pain questionnaire (MPQ). The menthol was applied to a site on the volar forearm. Participants also had their cold pain thresholds (CPT) evaluated at the same site using a contact thermode. RESULTS There were significant concentration-dependent effects for intensity of cold, unpleasantness and pain VAS: cold F(2,62) = 8.67, p < 0.001; unpleasantness χ2(2) = 14.14, p < 0.001; χ2(2) = 11.74, p = 0.003, with moderate effect sizes for unpleasantness and pain. There were also significant concentration dependent effects for descriptor indices, pain rating index (PRI) F(2,62) = 26.33, p < 0.001; number of words chosen (NWC) F(2,62) = 19.62, p < 0.001, with large effect sizes for 10-20% and 10-30% comparisons. Significant correlations were seen between measures of unpleasantness, pain, PRI, NWC and CPT dependent on menthol concentration. CONCLUSION Topical menthol has potential as a stimulus to evaluate cold hyperalgesia.
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Affiliation(s)
- Anthony Wright
- School of Physiotherapy and Exercise Science, Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
| | - Heather A E Benson
- School of Pharmacy and Biomedical Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
| | - Penny Moss
- School of Physiotherapy and Exercise Science, Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
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Weyer-Menkhoff I, Lötsch J. Human pharmacological approaches to TRP-ion-channel-based analgesic drug development. Drug Discov Today 2018; 23:2003-2012. [PMID: 29969684 DOI: 10.1016/j.drudis.2018.06.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 06/07/2018] [Accepted: 06/27/2018] [Indexed: 12/19/2022]
Abstract
The discovery of novel analgesic drug targets is an active research topic owing to insufficient treatment options for persisting pain. Modulators of temperature-sensing transient receptor potential ion channels (thermoTRPs), in particular TRPV1, TRPV2, TRPM8 and TRPA1, have reached clinical development. This requires access for TRP channels and the effects of specific modulators in humans. This is currently possible via (i) the study of TRP channel function in human-derived cell lines, (ii) immunohistochemical visualization of TRP channel expression in human tissues, (iii) human experimental pain models employing sensitization by means of topical application of TRP channel activators including capsaicin (TRPV1), menthol (TRPM8), mustard oil and cinnamaldehyde (TRPA1), and (iv) the study of phenotypic consequences of human TRP gene variants.
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Affiliation(s)
- Iris Weyer-Menkhoff
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany.
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Dose-response study of topical allyl isothiocyanate (mustard oil) as a human surrogate model of pain, hyperalgesia, and neurogenic inflammation. Pain 2018; 158:1723-1732. [PMID: 28614189 DOI: 10.1097/j.pain.0000000000000979] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Despite being a ubiquitous animal pain model, the natural TRPA1-agonist allyl isothiocyanate (AITC, also known as "mustard oil") has only been sparsely investigated as a potential human surrogate model of pain, sensitization, and neurogenic inflammation. Its dose-response as an algogenic, sensitizing irritant remains to be elucidated in human skin. Three concentrations of AITC (10%, 50%, and 90%) and vehicle (paraffin) were applied for 5 minutes to 3 × 3 cm areas on the volar forearms in 14 healthy volunteers, and evoked pain intensity (visual analog scale 0-100 mm) and pain quality were assessed. In addition, a comprehensive battery of quantitative sensory tests was conducted, including assessment of mechanical and thermal sensitivity. Neurogenic inflammation was quantified using full-field laser perfusion imaging. Erythema and hyperpigmentation were assessed before, immediately after, and ≈64 hours after AITC exposure. AITC induced significant dose-dependent, moderate-to-severe spontaneous burning pain, mechanical and heat hyperalgesia, and dynamic mechanical allodynia (P < 0.05). No significant differences in induced pain hypersensitivity were observed between the 50% and 90% AITC concentrations. Acute and prolonged inflammation was evoked by all concentrations, and assessments by full-field laser perfusion imaging demonstrated a significant dose-dependent increase with a ceiling effect from 50% to 90%. Topical AITC application produces pain and somatosensory sensitization in a dose-dependent manner with optimal concentrations recommended to be >10% and ≤50%. The model is translatable to humans and could be useful in pharmacological proof-of-concept studies of TRPA1-antagonists, analgesics, and anti-inflammatory compounds or for exploratory clinical purposes, eg, loss- or gain-of-function in peripheral neuropathies.
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De Caro C, Russo R, Avagliano C, Cristiano C, Calignano A, Aramini A, Bianchini G, Allegretti M, Brandolini L. Antinociceptive effect of two novel transient receptor potential melastatin 8 antagonists in acute and chronic pain models in rat. Br J Pharmacol 2018; 175:1691-1706. [PMID: 29485712 DOI: 10.1111/bph.14177] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 01/23/2018] [Accepted: 02/05/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Transient receptor potential (TRP) channels are a superfamily of non-selective cation permeable channels involved in peripheral sensory signalling. Animal studies have shown that several TRPs are important players in pain modulation. Among them, the TRP melastatin 8 (TRPM8) has elicited more interest for its controversial role in nociception. This channel, expressed by a subpopulation of sensory neurons in dorsal root ganglia (DRG) and trigeminal ganglia (TG), is activated by cold temperatures and cooling agents. In experimental neuropathic pain models, an up-regulation of this receptor in DRG and TG has been observed, suggesting a key role for TRPM8 in the development and maintenance of pain. Consistent with this hypothesis, TRPM8 knockout mice are less responsive to pain stimuli. EXPERIMENTAL APPROACH In this study, the therapeutic potential and efficacy of two novel TRPM8 antagonists, DFL23693 and DFL23448, were tested. KEY RESULTS Two potent and selective TRPM8 antagonists with distinct pharmacokinetic profiles, DFL23693 and DFL23448, have been fully characterized in vitro. In vivo studies in well-established models, namely, the wet-dog shaking test and changes in body temperature, confirmed their ability to block the TRPM8 channel. Finally, TRPM8 blockage resulted in a significant antinociceptive effect in formalin-induced orofacial pain and in chronic constriction injury-induced neuropathic pain, confirming an important role for this channel in pain perception. CONCLUSION AND IMPLICATIONS Our findings, in agreement with previous literature, encourage further studies for a better comprehension of the therapeutic potential of TRPM8 blockers as novel agents for pain management.
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Affiliation(s)
- Carmen De Caro
- Department of Pharmacy, University of Naples Federico II, Naples, Italy.,Department of Science of Health, School of Medicine and Surgery, University of Catanzaro, Catanzaro, Italy
| | - Roberto Russo
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Carmen Avagliano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Claudia Cristiano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Antonio Calignano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
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Wang S, Zhang D, Hu J, Jia Q, Xu W, Su D, Song H, Xu Z, Cui J, Zhou M, Yang J, Xiao J. A clinical and mechanistic study of topical borneol-induced analgesia. EMBO Mol Med 2018; 9:802-815. [PMID: 28396565 PMCID: PMC5452010 DOI: 10.15252/emmm.201607300] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Bingpian is a time‐honored herb in traditional Chinese medicine (TCM). It is an almost pure chemical with a chemical composition of (+)‐borneol and has been historically used as a topical analgesic for millennia. However, the clinical efficacy of topical borneol lacks stringent evidence‐based clinical studies and verifiable scientific mechanism. We examined the analgesic efficacy of topical borneol in a randomized, double‐blind, placebo‐controlled clinical study involving 122 patients with postoperative pain. Topical application of borneol led to significantly greater pain relief than placebo did. Using mouse models of pain, we identified the TRPM8 channel as a molecular target of borneol and showed that topical borneol‐induced analgesia was almost exclusively mediated by TRPM8, and involved a downstream glutamatergic mechanism in the spinal cord. Investigation of the actions of topical borneol and menthol revealed mechanistic differences between borneol‐ and menthol‐induced analgesia and indicated that borneol exhibits advantages over menthol as a topical analgesic. Our work demonstrates that borneol, which is currently approved by the US FDA to be used only as a flavoring substance or adjuvant in food, is an effective topical pain reliever in humans and reveals a key part of the molecular mechanism underlying its analgesic effect.
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Affiliation(s)
- Shu Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Ion Channel Research and Drug Development Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China .,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China
| | - Dan Zhang
- Department of Orthopedic Oncology, Shanghai Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Jinsheng Hu
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Ion Channel Research and Drug Development Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China
| | - Qi Jia
- Department of Orthopedic Oncology, Shanghai Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Wei Xu
- Department of Orthopedic Oncology, Shanghai Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Deyuan Su
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Ion Channel Research and Drug Development Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China
| | - Hualing Song
- Department of Preventive Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zhichun Xu
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Ion Channel Research and Drug Development Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China
| | - Jianmin Cui
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Ion Channel Research and Drug Development Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, USA
| | - Ming Zhou
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Ion Channel Research and Drug Development Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Jian Yang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Ion Channel Research and Drug Development Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China .,Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Jianru Xiao
- Department of Orthopedic Oncology, Shanghai Changzheng Hospital, The Second Military Medical University, Shanghai, China
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Zhou P, Chen Y, Zhang J, Wang K, Svensson P. Quantitative sensory testing for assessment of somatosensory function in human oral mucosa: a review. Acta Odontol Scand 2018; 76:13-20. [PMID: 28929829 DOI: 10.1080/00016357.2017.1375554] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE This narrative review provides an overview of the quantitative sensory testing (QST) to assess somatosensory function in human oral mucosa. MATERIAL AND METHODS A literature search was conducted in the PubMed database to identify studies in vivo on human oral mucosa using QST methods. A list of 149 articles was obtained and screened. A total of 36 relevant articles remained and were read in full text. Manual search of the reference lists identified eight additional relevant studies. A total of 44 articles were included for final assessment. RESULTS The included studies were divided into six categories according to the study content and objective. In each category, there was a great variety of aims, methods, participants and outcome measures. The application of QST has nevertheless helped to monitor somatosensory function in experimental models of intraoral pain, effects of local anesthesia, after oral and maxillofacial surgery and after prosthodontic and orthodontic treatment. CONCLUSIONS QST has been proved to be sufficiently stable and reliable, and valuable information has been obtained regarding somatosensory function in healthy volunteers, special populations and orofacial pain patients. However, as most of the studies were highly heterogeneous, the results are difficult to compare quantitatively. A standardized intraoral QST protocol is recommended and expected to help advance a mechanism-based assessment of neuropathies and other intraoral pain conditions.
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Affiliation(s)
- Pin Zhou
- Department of General Dentistry, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
- Department of Stomatology, The first people’s hospital of Lianyungang City, Lianyungang, China
| | - Yaming Chen
- Department of General Dentistry, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
- Orofacial Pain and TMD Research Unit, Institute of Stomatology, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
| | - Jinglu Zhang
- Department of General Dentistry, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
- Orofacial Pain and TMD Research Unit, Institute of Stomatology, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China
| | - Kelun Wang
- Center for Sensory–Motor Interaction (SMI), Aalborg University, Aalborg, Denmark
| | - Peter Svensson
- Section of Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
- Department of Dental Medicine, Karolinska Institutet, Huddinge, Sweden
- Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus University, Aarhus, Denmark
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22
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Abstract
The sensation of pain plays a vital protecting role, alerting organisms about potentially damaging stimuli. Tissue injury is detected by nerve endings of specialized peripheral sensory neurons called nociceptors that are equipped with different ion channels activated by thermal, mechanic, and chemical stimuli. Several transient receptor potential channels have been identified as molecular transducers of thermal stimuli in pain-sensing neurons. Skin injury or inflammation leads to increased sensitivity to thermal and mechanic stimuli, clinically defined as allodynia or hyperalgesia. This hypersensitivity is also characteristic of systemic inflammatory disorders and neuropathic pain conditions. Mechanisms of thermal hyperalgesia include peripheral sensitization of nociceptor afferents and maladaptive changes in pain-encoding neurons within the central nervous system. An important aspect of pain management involves attempts to minimize the development of nociceptor hypersensitivity. However, knowledge about the cellular and molecular mechanisms causing thermal hyperalgesia and allodynia in human subjects is still limited, and such knowledge would be an essential step for the development of more effective therapies.
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Affiliation(s)
- Félix Viana
- Alicante Institute of Neurosciences, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, San Juan de Alicante, Spain.
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23
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Analgesic-Like Activity of Essential Oil Constituents: An Update. Int J Mol Sci 2017; 18:ijms18122392. [PMID: 29232831 PMCID: PMC5751100 DOI: 10.3390/ijms18122392] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 11/03/2017] [Accepted: 11/03/2017] [Indexed: 12/18/2022] Open
Abstract
The constituents of essential oils are widely found in foods and aromatic plants giving characteristic odor and flavor. However, pharmacological studies evidence its therapeutic potential for the treatment of several diseases and promising use as compounds with analgesic-like action. Considering that pain affects a significant part of the world population and the need for the development of new analgesics, this review reports on the current studies of essential oils’ chemical constituents with analgesic-like activity, including a description of their mechanisms of action and chemical aspects.
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Krishnan-Sarin S, Green BG, Kong G, Cavallo DA, Jatlow P, Gueorguieva R, Buta E, O’Malley SS. Studying the interactive effects of menthol and nicotine among youth: An examination using e-cigarettes. Drug Alcohol Depend 2017; 180:193-199. [PMID: 28915478 PMCID: PMC5659733 DOI: 10.1016/j.drugalcdep.2017.07.044] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/25/2017] [Accepted: 07/30/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Tobacco products containing menthol are widely used by youth. We used e-cigarettes to conduct an experimental evaluation of the independent and interactive effects of menthol and nicotine among youth. PROCEDURES Pilot chemosensory experiments with fourteen e-cigarette users identified low (barely perceptible, 0.5%) and high (similar to commercial e-liquid, 3.5%) menthol concentrations. Sixty e-cigarette users were randomized to a nicotine concentration (0mg/ml, 6mg/ml, 12mg/ml) and participated in 3 laboratory sessions. During each session, they received their assigned nicotine concentration, along with one of three menthol concentrations in random counterbalanced order across sessions (0, 0.5%, 3.5%), and participated in three fixed-dose, and an ad-lib, puffing period. Urinary menthol glucuronide and salivary nicotine levels validated menthol and nicotine exposure. We examined changes in e-cigarette liking/wanting and taste, coolness, stimulant effects, nicotine withdrawal and ad-lib use. RESULTS Overall, the high concentration of menthol (3.5%) significantly increased e-cigarette liking/wanting relative to no menthol (p<0.001); there was marginal evidence of nicotine* menthol interactions (p=0.06), with an increase in liking/wanting when 3.5% menthol was combined with 12mg/ml nicotine, but not 6mg/ml nicotine. Importantly, both 0.5% and 3.5% menthol concentrations significantly improved taste and increased coolness. We did not observe nicotine or menthol-related changes in stimulant effects, nicotine withdrawal symptoms or ad-lib use. CONCLUSIONS Menthol, even at very low doses, alters the appeal of e-cigarettes among youth. Further, menthol enhances positive rewarding effects of high nicotine-containing e-cigarettes among youth.
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Affiliation(s)
| | - Barry G. Green
- The John B. Pierce Laboratory and Department of Surgery, Yale University School of Medicine
| | - Grace Kong
- Department of Psychiatry, Yale University School of Medicine
| | - Dana A. Cavallo
- Department of Psychiatry, Yale University School of Medicine
| | - Peter Jatlow
- Department of Laboratory Medicine, Yale University School of Medicine
| | | | - Eugenia Buta
- Department of Biostatistics, Yale University School of Public Health
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25
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Oz M, El Nebrisi EG, Yang KHS, Howarth FC, Al Kury LT. Cellular and Molecular Targets of Menthol Actions. Front Pharmacol 2017; 8:472. [PMID: 28769802 PMCID: PMC5513973 DOI: 10.3389/fphar.2017.00472] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/03/2017] [Indexed: 02/04/2023] Open
Abstract
Menthol belongs to monoterpene class of a structurally diverse group of phytochemicals found in plant-derived essential oils. Menthol is widely used in pharmaceuticals, confectionary, oral hygiene products, pesticides, cosmetics, and as a flavoring agent. In addition, menthol is known to have antioxidant, anti-inflammatory, and analgesic effects. Recently, there has been renewed awareness in comprehending the biological and pharmacological effects of menthol. TRP channels have been demonstrated to mediate the cooling actions of menthol. There has been new evidence demonstrating that menthol can significantly influence the functional characteristics of a number of different kinds of ligand and voltage-gated ion channels, indicating that at least some of the biological and pharmacological effects of menthol can be mediated by alterations in cellular excitability. In this article, we examine the results of earlier studies on the actions of menthol with voltage and ligand-gated ion channels.
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Affiliation(s)
- Murat Oz
- Department of Pharmacology, College of Medicine and Health Sciences, United Arab Emirates UniversityAl Ain, United Arab Emirates.,Department of Basic Medical Sciences, College of Medicine, Qatar UniversityDoha, Qatar
| | - Eslam G El Nebrisi
- Department of Pharmacology, College of Medicine and Health Sciences, United Arab Emirates UniversityAl Ain, United Arab Emirates
| | - Keun-Hang S Yang
- Department of Biological Sciences, Schmid College of Science and Technology, Chapman UniversityOrange, CA, United States
| | - Frank C Howarth
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates UniversityAl Ain, United Arab Emirates
| | - Lina T Al Kury
- Department of Health Sciences, College of Natural and Health Sciences, Zayed UniversityAbu Dhabi, United Arab Emirates
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Abstract
Itch, or pruritus, is a hallmark feature of atopic dermatitis (AD). The impact of AD-related pruritus can range from mildly distressing or distracting to completely disabling. Traditionally, management of itch in AD patients has focused on restoring the altered skin barrier with topical emollients and/or reducing inflammation. A growing emphasis has been placed on directly targeting the neural transmission pathways that mediate itch signaling. Off-label use of neuromodulatory agents has helped reduce this aggravating symptom in atopic patients. This article reviews the current literature on the use of neuromodulatory agents and nonpharmacologic alternative therapies used to treat AD-related pruritus.
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Affiliation(s)
- Sarina B Elmariah
- Department of Dermatology, Harvard Medical School, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
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27
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Development of TRPM8 Antagonists to Treat Chronic Pain and Migraine. Pharmaceuticals (Basel) 2017; 10:ph10020037. [PMID: 28358322 PMCID: PMC5490394 DOI: 10.3390/ph10020037] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 03/16/2017] [Accepted: 03/23/2017] [Indexed: 01/17/2023] Open
Abstract
A review. Development of pharmaceutical antagonists of transient receptor potential melastatin 8 (TRPM8) have been pursued for the treatment of chronic pain and migraine. This review focuses on the current state of this progress.
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28
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Mentha spicata as natural analgesia for treatment of pain in osteoarthritis patients. Complement Ther Clin Pract 2016; 26:1-4. [PMID: 28107842 DOI: 10.1016/j.ctcp.2016.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 11/01/2016] [Indexed: 02/06/2023]
Abstract
Osteoarthritis, as the major cause of chronic musculoskeletal pain, impacts people aged 45 and above. The first line analgesic treatments have reported minimal short term effects. The use of essential oils as pain killer has increased, recently. Mentha spicata, or spearmint essential oil is famous due to its anti-flatulence effects, but one less known biological activity of spearmint is its analgesic activity. The aim of our study was to confirm the analgesic effects of M. spicata essential oil. In this review, we evaluated the articles on analgesic activities of M. spicata essential oil from different relevant databases (PubMed, Science Direct, Wiley, Taylor & Francis, and Springer) without limitation up to April 30, 2016. Different animal studies have reported the analgesic effects of M. spicata essential oil and its main abundant compounds such as carvone, limonene and menthol, also, the efficacy and safety of spearmint oil in reducing of pain severity were confirmed in osteoarthritis patients. In spite of the beneficial effects of spearmint oil in reducing of pain, other large clinical trials are required to confirm the efficacy and safety of M. spicata oil.
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High-Concentration L-Menthol Exhibits Counter-Irritancy to Neurogenic Inflammation, Thermal and Mechanical Hyperalgesia Caused by Trans-cinnamaldehyde. THE JOURNAL OF PAIN 2016; 17:919-29. [PMID: 27260636 DOI: 10.1016/j.jpain.2016.05.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/21/2016] [Accepted: 05/10/2016] [Indexed: 11/20/2022]
Abstract
UNLABELLED The transient receptor potential cation channel subfamily M 8 (TRPM8) agonist L-menthol has been used traditionally for its topical counterirritant properties. Although the use of topical L-menthol for pain is casuistically established, evidence regarding its efficacy is negligible. This study aimed to characterize the effect of L-menthol as a counterirritant on cutaneous pain and hyperalgesia provoked by topical application of the transient receptor potential cation channel, subfamily A, member 1 (TRPA1) agonist trans-cinnamaldehyde (CA). In a randomized, double-blinded study CA was applied to a 3 × 3-cm area of the volar forearm evoking neurogenic inflammation, pain, mechanical, and thermal hyperalgesia in 14 healthy volunteers. In different sessions, 10% CA alone or 40% L-menthol applied simultaneously with 10% CA were administered for 20 minutes, throughout which the subjects rated the pain intensity on a visual analogue scale of 0 to 10. Extensive quantitative sensory testing was conducted and superficial blood flow (neurogenic inflammation) was recorded. Administration of CA evoked spontaneous pain, neurogenic inflammation, thermal hyperalgesia, and primary and secondary mechanical hyperalgesia. Coadministration of topical L-menthol reduced spontaneous pain intensity (P < .01), neurogenic inflammation (P < .01), primary mechanical hyperalgesia (P < .05), secondary mechanical hyperalgesia (P < .05), and heat hyperalgesia (P < .05), but not cold hyperalgesia. L-menthol exhibited inhibitory effects on simultaneously established pain, hypersensitivity, and neurogenic inflammation in a human TRPA1-induced pain model. Potent TRPM8 agonists could be useful as topical antihyperalgesics. The study and the trial protocol is registered and approved by the local research ethics committee under the jurisdiction of the Danish Medicines Agency number N-20130005. The protocol also is registered at Clinicaltrials.gov under NCT02653703. PERSPECTIVE Drugs interacting with transient receptor potential channels are of great therapeutic potential. In the present study we established cutaneous pain and hyperalgesia using the TRPA1 agonist CA. Subsequently, we showed that the frequently used topical counterirritant and TRPM8 agonist, L-menthol, decreased evoked pain, hyperalgesia, and inflammation, indicating direct and indirect antinociceptive mechanisms.
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30
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Cold and L-menthol-induced sensitization in healthy volunteers--a cold hypersensitivity analogue to the heat/capsaicin model. Pain 2016; 156:880-889. [PMID: 25719613 DOI: 10.1097/j.pain.0000000000000123] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Topical high-concentration L-menthol is the only established human experimental pain model to study mechanisms underlying cold hyperalgesia. We aimed at investigating the combinatorial effect of cold stimuli and topical L-menthol on cold pain and secondary mechanical hyperalgesia. Analogue to the heat-capsaicin model on skin sensitization, we proposed that cold/menthol enhances or prolong L-menthol-evoked sensitization. Topical 40% L-menthol or vehicle was applied (20 minutes) on the volar forearms of 20 healthy females and males (age, 28.7 ± 0.6 years). Cold stimulation of 5°C for 5 minutes was then applied to the treated area 3 times with 40-minute intervals. Cold detection threshold and pain, mechanical hyperalgesia (pinprick), static and dynamic mechanical allodynia (von Frey and brush), skin blood flow (laser speckle), and temperature (thermocamera) were assessed. Cold detection threshold and cold pain threshold (CPT) increased after L-menthol and remained high after the cold rekindling cycles (P < 0.001). L-menthol evoked secondary hyperalgesia to pinprick (P < 0.001) particularly in females (P < 0.05) and also induced secondary allodynia to von Frey and brush (P < 0.001). Application of cold stimuli kept these areas enlarged with a higher response in females to brush after the third cold cycle (P < 0.05). Skin blood flow increased after L-menthol (P < 0.001) and stayed stable after cold cycles. Repeated application of cold on skin treated by L-menthol facilitated and prolonged L-menthol-induced cold pain and hyperalgesia. This model may prove beneficial for testing analgesic compounds when a sufficient duration of time is needed to see drug effects on CPT or mechanical hypersensitivity.
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Arendt Nielsen T, Nielsen BP, Wang K, Arendt-Nielsen L, Boudreau SA. Psychophysical and Vasomotor Responses of the Oral Tissues: A Nicotine Dose-Response and Menthol Interaction Study. Nicotine Tob Res 2015; 18:596-603. [PMID: 26242288 DOI: 10.1093/ntr/ntv163] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 07/22/2015] [Indexed: 01/21/2023]
Abstract
INTRODUCTION This study implemented an intra-oral test-platform to assess the sensory, psychophysical, and vasomotor responses to nicotine and menthol, alone or in combination. METHODS Two double-blinded, placebo-controlled, randomized, cross-over studies, including healthy nonsmoking participants were performed. Study I: A dose-response relationship (N = 20) between 0, 2, and 4 mg nicotine gum. Study II: An interaction response (N = 22) to 30 mg menthol and 4 mg nicotine alone or in combination. Heart rate, blood pressure, tactile and thermosensory thresholds, intra-oral blood flow and temperature, pain/irritation intensities/locations, McGill Pain Questionnaire, and taste experience were assessed before, during or after the completion of a standardized chewing regime. RESULTS A dose-response elevation in heart rate was attenuated when nicotine was combined with menthol. Blood flow, temperature, and warm-detection thresholds, as assessed on the tongue, similarly increased for all gums. Pain intensity and taste experiences were similar between nicotine doses. Nicotine attenuated the sweet, cooling, and freshening sensation of menthol. Within the first 4 minutes, menthol reduced the intensity but not the area of nicotine-induced pain and irritation. The 4-mg nicotine dose led to a continued increase in the intensity and area of irritation in the throat post-chewing. Moreover, one-half of participants responded to menthol as an irritant, and these individuals demonstrated larger areas of nicotine-induced irritation in the throat post-chewing. CONCLUSIONS The intra-oral test platform provides a basis to optimize the assessment of nicotine-related taste and sensory experiences and can be used in future studies for profiling nicotine gum.
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Affiliation(s)
- Thomas Arendt Nielsen
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, School of Medicine, Aalborg University, Aalborg, Denmark
| | | | - Kelun Wang
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, School of Medicine, Aalborg University, Aalborg, Denmark
| | - Lars Arendt-Nielsen
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, School of Medicine, Aalborg University, Aalborg, Denmark
| | - Shellie A Boudreau
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, School of Medicine, Aalborg University, Aalborg, Denmark;
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Abstract
Chemesthetic compounds, responsible for sensations such as burning, cooling, and astringency, are difficult stimuli to work with, especially when the evaluation task requires retasting. Here, we developed a protocol by which chemesthetic compounds can be assessed using sorting. We compared the performance of two cohorts of untrained assessors on this task, one with nose clips and the other without. Similarity matrices were analyzed using multidimensional scaling (MDS) to produce perceptual maps for the two cohorts. Overall, the groupings from the nose open cohort tended to follow a biological basis, consistent with previous findings that suggest compounds that activate a common receptor will elicit similar sensations. The nose-open and nose-pinched cohorts generated significantly different maps. The nose-pinched cohort had a higher variance in the MDS solution than the nose-open group. While the nose-open cohort generated seven clusters, the nose-pinched cohort generated only two clusters, seemingly based on the ready identification of chemesthetic sensations or not. There was less consensus regarding the attributes used to describe the samples in the nose-pinched cohort than in the nose-open cohort as well, as this cohort collectively generated more attributes but fewer were significant in regression.
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33
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Abstract
Chemesthetic compounds, responsible for sensations such as burning, cooling, and astringency, are difficult stimuli to work with, especially when the evaluation task requires retasting. Here, we developed a protocol by which chemesthetic compounds can be assessed using sorting. We compared the performance of two cohorts of untrained assessors on this task, one with nose clips and the other without. Similarity matrices were analyzed using multidimensional scaling (MDS) to produce perceptual maps for the two cohorts. Overall, the groupings from the nose open cohort tended to follow a biological basis, consistent with previous findings that suggest compounds that activate a common receptor will elicit similar sensations. The nose-open and nose-pinched cohorts generated significantly different maps. The nose-pinched cohort had a higher variance in the MDS solution than the nose-open group. While the nose-open cohort generated seven clusters, the nose-pinched cohort generated only two clusters, seemingly based on the ready identification of chemesthetic sensations or not. There was less consensus regarding the attributes used to describe the samples in the nose-pinched cohort than in the nose-open cohort as well, as this cohort collectively generated more attributes but fewer were significant in regression.
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Affiliation(s)
- Nadia Byrnes
- Sensory Evaluation Center, College of Agricultural Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Food Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
| | | | - John E. Hayes
- Sensory Evaluation Center, College of Agricultural Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Food Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
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34
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Effects of monoterpenes on ion channels of excitable cells. Pharmacol Ther 2015; 152:83-97. [PMID: 25956464 DOI: 10.1016/j.pharmthera.2015.05.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 04/23/2015] [Indexed: 11/20/2022]
Abstract
Monoterpenes are a structurally diverse group of phytochemicals and a major constituent of plant-derived 'essential oils'. Monoterpenes such as menthol, carvacrol, and eugenol have been utilized for therapeutical purposes and food additives for centuries and have been reported to have anti-inflammatory, antioxidant and analgesic actions. In recent years there has been increasing interest in understanding the pharmacological actions of these molecules. There is evidence indicating that monoterpenes can modulate the functional properties of several types of voltage and ligand-gated ion channels, suggesting that some of their pharmacological actions may be mediated by modulations of ion channel function. In this report, we review the literature concerning the interaction of monoterpenes with various ion channels.
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Thermosensitive transient receptor potential (TRP) channel agonists and their role in mechanical, thermal and nociceptive sensations as assessed using animal models. CHEMOSENS PERCEPT 2015; 8:96-108. [PMID: 26388966 DOI: 10.1007/s12078-015-9176-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION The present paper summarizes research using animal models to investigate the roles of thermosensitive transient receptor potential (TRP) channels in somatosensory functions including touch, temperature and pain. We present new data assessing the effects of eugenol and carvacrol, agonists of the warmth-sensitive TRPV3, on thermal, mechanical and pain sensitivity in rats. METHODS Thermal sensitivity was assessed using a thermal preference test, which measured the amount of time the animal occupied one of two adjacent thermoelectric plates set at different temperatures. Pain sensitivity was assessed as an increase in latency of hindpaw withdrawal away from a noxious thermal stimulus directed to the plantar hindpaw (Hargreaves test). Mechanical sensitivity was assessed by measuring the force exerted by an electronic von Frey filament pressed against the plantar surface that elicited withdrawal. RESULTS Topical application of eugenol and carvacrol did not significantly affect thermal preference, although there was a trend toward avoidance of the hotter surface in a 30 vs. 45°C preference test for rats treated with 1 or 10% eugenol and carvacrol. Both eugenol and carvacrol induced a concentration-dependent increase in thermal withdrawal latency (analgesia), with no significant effect on mechanosensitivity. CONCLUSIONS The analgesic effect of eugenol and carvacrol is consistent with previous studies. The tendency for these chemicals to increase the avoidance of warmer temperatures suggests a possible role for TRPV3 in warmth detection, also consistent with previous studies. Additional roles of other thermosensitive TRP channels (TRPM8 TRPV1, TRPV2, TRPV4, TRPM3, TRPM8, TRPA1, TRPC5) in touch, temperature and pain are reviewed.
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Naganawa T, Baad-Hansen L, Ando T, Svensson P. Influence of topical application of capsaicin, menthol and local anesthetics on intraoral somatosensory sensitivity in healthy subjects: temporal and spatial aspects. Exp Brain Res 2015; 233:1189-99. [PMID: 25596697 DOI: 10.1007/s00221-015-4200-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/02/2014] [Indexed: 10/24/2022]
Abstract
The aim of this study was to investigate temporal and spatial aspects of somatosensory changes after topical application of capsaicin, menthol and local anesthetics (LA) on the gingiva with the use of intraoral palpometers and thermal devices. Sixteen healthy volunteers (eight male, eight female) participated. Four topical preparations (capsaicin, menthol, LA and Vaseline as a control) were randomly applied to the gingiva around the first premolar in the upper jaw via individual oral templates, which allowed spatial mapping of somatosensory changes at and adjacent to the site of application. The topical drugs were applied for 15 min in a randomized and balanced sequence. The perceived preparation-evoked pain intensity was recorded with the use of 0-10 visual analog scales (VAS). Standardized mechanical and thermal stimuli were applied before, during and up to 30 min after the topical applications, and numerical rating scales (NRS) were used to score the perceived intensity of the stimuli. Peak VAS, area under the curve and mean VAS preparation-evoked pain scores for capsaicin, menthol, LA and control were compared with paired t tests. NRS scores for mechanical and thermal test stimuli were analyzed with four-way repeated measurements analyses of variance. Capsaicin evoked significantly higher VAS pain parameters as well as higher NRS scores to heat stimuli than control (P < 0.029). There were no significant differences in stimulus-evoked NRS scores between the menthol and control conditions (P = 0.518), but LA caused significantly lower stimulus-evoked NRS scores compared with control (P < 0.001). Post hoc tests showed that capsaicin caused sensitization to heat stimuli at and adjacent to the application area. In conclusion, this study for the first time demonstrates the time course of capsaicin-evoked heat hyperalgesia in and outside the site of application at the oral mucosa (primary and secondary hyperalgesia).
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Affiliation(s)
- Takuya Naganawa
- Section of Clinical Oral Physiology, Department of Dentistry, Health, Aarhus University, Vennelyst Boulevard 9, 8000, Åarhus C, Denmark,
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Lau BK, Karim S, Goodchild AK, Vaughan CW, Drew GM. Menthol enhances phasic and tonic GABAA receptor-mediated currents in midbrain periaqueductal grey neurons. Br J Pharmacol 2014; 171:2803-13. [PMID: 24460753 DOI: 10.1111/bph.12602] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 01/05/2014] [Accepted: 01/19/2014] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Menthol, a naturally occurring compound in the essential oil of mint leaves, is used for its medicinal, sensory and fragrant properties. Menthol acts via transient receptor potential (TRPM8 and TRPA1) channels and as a positive allosteric modulator of recombinant GABAA receptors. Here, we examined the actions of menthol on GABAA receptor-mediated currents in intact midbrain slices. EXPERIMENTAL APPROACH Whole-cell voltage-clamp recordings were made from periaqueductal grey (PAG) neurons in midbrain slices from rats to determine the effects of menthol on GABAA receptor-mediated phasic IPSCs and tonic currents. KEY RESULTS Menthol (150-750 μM) produced a concentration-dependent prolongation of spontaneous GABAA receptor-mediated IPSCs, but not non-NMDA receptor-mediated EPSCs throughout the PAG. Menthol actions were unaffected by TRPM8 and TRPA1 antagonists, tetrodotoxin and the benzodiazepine antagonist, flumazenil. Menthol also enhanced a tonic current, which was sensitive to the GABAA receptor antagonists, picrotoxin (100 μM), bicuculline (30 μM) and Zn(2+) (100 μM), but unaffected by gabazine (10 μM) and a GABAC receptor antagonist, 1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid hydrate (TPMPA; 50 μM). In addition, menthol potentiated currents induced by the extrasynaptic GABAA receptor agonist THIP/gaboxadol (10 μM). CONCLUSIONS AND IMPLICATIONS These results suggest that menthol positively modulates both synaptic and extrasynaptic populations of GABAA receptors in native PAG neurons. The development of agents that potentiate GABAA -mediated tonic currents and phasic IPSCs in a manner similar to menthol could provide a basis for novel GABAA -related pharmacotherapies.
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Affiliation(s)
- Benjamin K Lau
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, The University of Sydney at Royal North Shore Hospital, St Leonards, NSW, Australia
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Helfert SM, Reimer M, Höper J, Baron R. Individualized pharmacological treatment of neuropathic pain. Clin Pharmacol Ther 2014; 97:135-42. [PMID: 25670518 DOI: 10.1002/cpt.19] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/21/2014] [Indexed: 12/15/2022]
Abstract
Patients with the same disease may suffer from completely different pain symptoms yet receive the same drug treatment. Several studies elucidate neuropathic pain and treatment response in human surrogate pain models. They show promising results toward a patient stratification according to the mechanisms underlying the pain, as reflected in their symptoms. Several promising new drugs produced negative study results in clinical phase III trials. However, retrospective analysis of treatment response based on baseline pain phenotyping could demonstrate positive results for certain subgroups of patients. Thus, a prospective classification of patients according to pain phenotype may play an increasingly important role in personalized treatment of neuropathic pain states. A recent prospective study using stratification based on pain-related sensory abnormalities confirmed the concept of personalized pharmacological treatment of neuropathic pain.
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Affiliation(s)
- S M Helfert
- Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital, Kiel, Germany
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Hu X, Liu Y, Zeng G, Xu W, Hu X, Zhu Z, Zhang P, Wang Y. Effects of d-menthol stress on the growth of and microcystin release by the freshwater cyanobacterium Microcystis aeruginosa FACHB-905. CHEMOSPHERE 2014; 113:30-5. [PMID: 25065786 DOI: 10.1016/j.chemosphere.2014.03.084] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 03/27/2014] [Accepted: 03/28/2014] [Indexed: 05/26/2023]
Abstract
The effects of d-menthol on the growth of Microcystis aeruginosa FACHB-905 and microcystin (MCY) concentration were evaluated by batch culture experiments. The algal biomass and the intracellular and extracellular MCY concentrations were evaluated during 5d incubation. After the d-menthol exposure, the dry weight of the cells gradually decreased; the decrease in the dry weight after 5d exposure was 29, 12, and 2mgL(-1) when the initial cell densities were 1.4×10(7), 1.2×10(6), and 2.9×10(5)cellmL(-1), respectively. The results indicate that the d-menthol exposure inhibited the cellular growth, thus also inhibiting the increase of the total MCY concentration. In the presence of d-menthol, the intracellular MCY was gradually released into the medium after the cell lysis. The extracellular MCY concentration in the medium was significantly higher in the d-menthol-exposed samples than in the control samples, confirming that d-menthol cannot decompose the extracellular MCY.
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Affiliation(s)
- Xi Hu
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China
| | - Yunguo Liu
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
| | - Guangming Zeng
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Weihua Xu
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Xinjiang Hu
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China
| | - Zhilin Zhu
- Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Pingyang Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China
| | - Yaqin Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China
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Patel R, Gonçalves L, Leveridge M, Mack SR, Hendrick A, Brice NL, Dickenson AH. Anti-hyperalgesic effects of a novel TRPM8 agonist in neuropathic rats: a comparison with topical menthol. Pain 2014; 155:2097-107. [PMID: 25083927 PMCID: PMC4220012 DOI: 10.1016/j.pain.2014.07.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 07/21/2014] [Accepted: 07/25/2014] [Indexed: 11/27/2022]
Abstract
Menthol has historically been used topically to alleviate various pain conditions. At low concentrations, this non-selective TRPM8 agonist elicits a cooling sensation, however higher concentrations result in cold hyperalgesia in normal subjects and paradoxically analgesia in neuropathic patients. Through behavioural and electrophysiological means, we examined whether this back-translated into a pre-clinical rodent model. Menthol was applied topically to the hind paws of naive and spinal nerve-ligated (SNL) rats. In behavioural assays, menthol did not affect withdrawal thresholds to mechanical stimulation and 10% and 40% menthol rarely sensitised withdrawals to innocuous cooling in naïve rats. However, in SNL rats, 10% and 40% menthol alleviated cold hypersensitivity. This was partly corroborated by in vivo electrophysiological recordings of dorsal horn lamina V/VI neurones. As several studies have implicated TRPM8 in analgesia, we examined whether a novel systemically available TRPM8 agonist, M8-Ag, had more potent anti-hyperalgesic effects than menthol in neuropathic rats. In vitro, M8-Ag activates TRPM8, expressed in HEK293 cells, with an EC50 of 44.97 nM. In vivo, M8-Ag inhibited neuronal responses to innocuous and noxious cooling in SNL rats with no effect in sham-operated rats. This effect was modality selective; M8-Ag did not alter neuronal responses to mechanical, heat or brush stimulation. In addition, M8-Ag attenuated behavioural hypersensitivity to innocuous cooling but not mechanical stimulation. These data suggest that menthol induced hyperalgesia is not consistently replicable in the rat and that the analgesic properties are revealed by injury. Systemic TRPM8 agonists might be beneficial in neuropathy without affecting normal cold sensitivity.
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Affiliation(s)
- Ryan Patel
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
| | - Leonor Gonçalves
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | | | | | | | | | - Anthony H Dickenson
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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Mahn F, Hüllemann P, Wasner G, Baron R, Binder A. Topical high-concentration menthol: reproducibility of a human surrogate pain model. Eur J Pain 2014; 18:1248-58. [PMID: 24777959 DOI: 10.1002/j.1532-2149.2014.484.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2014] [Indexed: 12/12/2022]
Abstract
BACKGROUND Human experimental pain models play an important role in studying neuropathic pain mechanisms. The objective of the present study was to test the reproducibility of the topical menthol model over a 1-week period. METHOD We performed an open, two-period study in 10 healthy volunteers with 40 menthol applications. The side of menthol application was randomly assigned. Two trial periods were separated by 1 week. Before and after applying menthol, selected quantitative sensory testing (QST) was performed. The area of mechanical pin-prick hyperalgesia was quantified. Spontaneous pain was recorded. RESULTS Application of menthol induced a statistically significant decrease in the cold pain threshold (CPT) (p < 0.001) and mechanical pain threshold and an increase in the mechanical pain sensitivity (MPS) (p < 0.001), indicating cold and mechanical (pin-prick) hyperalgesia. Test-retest reliability was best for CPT (r = 0.959) and MPS (r = 0.930). Intraclass correlation values showed excellent reliability for cold pain and MPS (ICC = 0.96, 0.89). The QST values post-menthol showed high inter-period correlation factors and no significant inter-period differences (paired t-test, t = 1.767-1.361; p = 0.111-0.988). The area size of mechanical hyperalgesia was not reliably reproducible. CONCLUSION For an observation period of 1 week, the signs of cold and mechanical hyperalgesia were reproducible with a highly significant correlation of about r = 0.8 and good agreement except for the area size of mechanical pin-prick hyperalgesia. These results demonstrate that the topical menthol pain model is suitable for pharmacological interventions repeated within an observation period of 1 week.
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Affiliation(s)
- F Mahn
- Division of Neurological Pain Research and Therapy, Department of Neurology, Christian-Albrechts-Universität Kiel, Germany
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42
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Olsen R, Andersen H, Møller H, Eskelund P, Arendt-Nielsen L. Somatosensory and vasomotor manifestations of individual and combined stimulation of TRPM8 and TRPA1 using topical L-menthol andtrans-cinnamaldehyde in healthy volunteers. Eur J Pain 2014; 18:1333-42. [DOI: 10.1002/j.1532-2149.2014.494.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2014] [Indexed: 11/09/2022]
Affiliation(s)
- R.V. Olsen
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - H.H. Andersen
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - H.G. Møller
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - P.W. Eskelund
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - L. Arendt-Nielsen
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
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43
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Teliban A, Bartsch F, Struck M, Baron R, Jänig W. Responses of intact and injured sural nerve fibers to cooling and menthol. J Neurophysiol 2014; 111:2071-83. [PMID: 24572095 DOI: 10.1152/jn.00287.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intact and injured cutaneous C-fibers in the rat sural nerve are cold sensitive, heat sensitive, and/or mechanosensitive. Cold-sensitive fibers are either low-threshold type 1 cold sensitive or high-threshold type 2 cold sensitive. The hypothesis was tested, in intact and injured afferent nerve fibers, that low-threshold cold-sensitive afferent nerve fibers are activated by the transient receptor potential melastatin 8 (TRPM8) agonist menthol, whereas high-threshold cold-sensitive C-fibers and cold-insensitive afferent nerve fibers are menthol insensitive. In anesthetized rats, activity was recorded from afferent nerve fibers in strands isolated from the sural nerve, which was either intact or crushed 6-12 days before the experiment distal to the recording site. In all, 77 functionally identified afferent C-fibers (30 intact fibers, 47 injured fibers) and 34 functionally characterized A-fibers (11 intact fibers, 23 injured fibers) were tested for their responses to menthol applied to their receptive fields either in the skin (10 or 20%) or in the nerve (4 or 8 mM). Menthol activated all intact (n = 12) and 90% of injured (n = 20/22) type 1 cold-sensitive C-fibers; it activated no intact type 2 cold-sensitive C-fibers (n = 7) and 1/11 injured type 2 cold-sensitive C-fibers. Neither intact nor injured heat- and/or mechanosensitive cold-insensitive C-fibers (n = 25) and almost no A-fibers (n = 2/34) were activated by menthol. These results strongly argue that cutaneous type 1 cold-sensitive afferent fibers are nonnociceptive cold fibers that use the TRPM8 transduction channel.
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Affiliation(s)
- Alina Teliban
- Physiologisches Institut, Christian-Albrechts-Universität zu Kiel, Kiel, Germany; and
| | - Fabian Bartsch
- Physiologisches Institut, Christian-Albrechts-Universität zu Kiel, Kiel, Germany; and
| | - Marek Struck
- Physiologisches Institut, Christian-Albrechts-Universität zu Kiel, Kiel, Germany; and
| | - Ralf Baron
- Division of Neurological Pain Research and Therapy, Department of Neurology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Wilfrid Jänig
- Physiologisches Institut, Christian-Albrechts-Universität zu Kiel, Kiel, Germany; and
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Kamatou GPP, Vermaak I, Viljoen AM, Lawrence BM. Menthol: a simple monoterpene with remarkable biological properties. PHYTOCHEMISTRY 2013; 96:15-25. [PMID: 24054028 DOI: 10.1016/j.phytochem.2013.08.005] [Citation(s) in RCA: 228] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 08/09/2013] [Indexed: 05/04/2023]
Abstract
Menthol is a cyclic monoterpene alcohol which possesses well-known cooling characteristics and a residual minty smell of the oil remnants from which it was obtained. Because of these attributes it is one of the most important flavouring additives besides vanilla and citrus. Due to this reason it is used in a variety of consumer products ranging from confections such as chocolate and chewing gum to oral-care products such as toothpaste as well as in over-the-counter medicinal products for its cooling and biological effects. Its cooling effects are not exclusive to medicinal use. Approximately one quarter of the cigarettes on the market contain menthol and small amounts of menthol are even included in non-mentholated cigarettes. Natural menthol is isolated exclusively from Mentha canadensis, but can also be synthesised on industrial scale through various processes. Although menthol exists in eight stereoisomeric forms, (-)-menthol from the natural source and synthesised menthol with the same structure is the most preferred isomer. The demand for menthol is high and it was previously estimated that the worldwide use of menthol was 30-32,000 metric tonnes per annum. Menthol is not a predominant compound of the essential oils as it can only be found as a constituent of a limited number of aromatic plants. These plants are known to exhibit biological activity in vitro and in vivo such as antibacterial, antifungal, antipruritic, anticancer and analgesic effects, and are also an effective fumigant. In addition, menthol is one of the most effective terpenes used to enhance the dermal penetration of pharmaceuticals. This review summarises the chemical and biological properties of menthol and highlights its cooling effects and toxicity.
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Affiliation(s)
- Guy P P Kamatou
- Department of Pharmaceutical Sciences, Faculty of Science, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa
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45
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Andersen H, Olsen R, Møller H, Eskelund P, Gazerani P, Arendt-Nielsen L. A review of topical high-concentration L-menthol as a translational model of cold allodynia and hyperalgesia. Eur J Pain 2013; 18:315-25. [DOI: 10.1002/j.1532-2149.2013.00380.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2013] [Indexed: 12/14/2022]
Affiliation(s)
- H.H. Andersen
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - R.V. Olsen
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - H.G. Møller
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - P.W. Eskelund
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - P. Gazerani
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
| | - L. Arendt-Nielsen
- Center for Sensory-Motor Interaction (SMI); Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Denmark
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Lu S, Baad-Hansen L, List T, Zhang Z, Svensson P. Somatosensory profiling of intra-oral capsaicin and menthol in healthy subjects. Eur J Oral Sci 2013; 121:29-35. [PMID: 23331421 DOI: 10.1111/eos.12014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2012] [Indexed: 11/30/2022]
Abstract
This study was designed to investigate the effect of surrogate orofacial pain models on the quantitative sensory testing (QST) profile in healthy participants. Capsaicin, menthol, or saline (control) were applied topically onto the gingiva of 15 healthy subjects for 15 min. During application, the subjects rated pain intensity on a score of 0-10, on an electronic visual analog scale (VAS). A standardized intra-oral QST protocol was performed before and immediately after application. Data obtained before and after application were compared using rank-sum tests, and QST profiles were made after Z-transformation. Application of capsaicin caused moderate levels of pain (VAS(peak) = 6.0 ± 0.7), and application of menthol produced mild levels of pain (VAS(peak) = 1.8 ± 0.6). Capsaicin induced hypersensitivity to warmth, heat pain and cold pain and hyposensitivity to mechanical stimuli. Menthol induced hypersensitivity to cold and warmth. Saline caused hypersensitivity to heat pain and hyposensitivity to mechanical stimuli. However, somatosensory profiles from Z-scores demonstrated sensory gains regarding warmth detection and heat pain only after application of capsaicin. In conclusion, a standardized battery of QST showed somatosensory changes after application of capsaicin, menthol and saline to the gingiva. However, the Z-score-based profiles may only reflect the most prominent somatosensory changes and thus represent a conservative approach for evaluation of data.
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Affiliation(s)
- Shengyi Lu
- Department of Prosthodontics, School of Stomatology, Capital Medical University, Beijing, China
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Topp R, Ledford ER, Jacks DE. Topical menthol, ice, peripheral blood flow, and perceived discomfort. J Athl Train 2013; 48:220-5. [PMID: 23672386 DOI: 10.4085/1062-6050-48.1.19] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT Injury management commonly includes decreasing arterial blood flow to the affected site in an attempt to reduce microvascular blood flow and edema and limit the induction of inflammation. Applied separately, ice and menthol gel decrease arterial blood flow, but the combined effects of ice and menthol gel on arterial blood flow are unknown. OBJECTIVES To compare radial artery blood flow, arterial diameter, and perceived discomfort before and after the application of 1 of 4 treatment conditions. DESIGN Experimental crossover design. SETTING Clinical laboratory. PARTICIPANTS OR OTHER PARTICIPANTS: Ten healthy men, 9 healthy women (mean age = 25.68 years, mean height = 1.73 m, mean weight = 76.73 kg). INTERVENTION(S) Four treatment conditions were randomly applied for 20 minutes to the right forearm of participants on 4 different days separated by at least 24 hours: (1) 3.5 mL menthol gel, (2) 0.5 kg of crushed ice, (3) 3.5 mL of menthol gel and 0.5 kg of crushed ice, or (4) no treatment (control). MAIN OUTCOME MEASURE(S) Using high-resolution ultrasound, we measured right radial artery diameter (cm) and blood flow (mL/min) every 5 minutes for 20 minutes after the treatment was applied. Discomfort with the treatment was documented using a 1-to-10 intensity scale. RESULTS Radial artery blood flow decreased (P < .05) from baseline in the ice (-20% to -24%), menthol (-17% to -24%), and ice and menthol (-36% to -39%) treatments but not in the control (3% to 9%) at 5, 10, and 15 minutes. At 20 minutes after baseline, only the ice (-27%) and combined ice and menthol (-38%) treatments exhibited reductions in blood flow (P < .05). Discomfort was less with menthol than with the ice treatment at 5, 10, and 20 minutes after application (P < .05). Arterial diameter and heart rate did not change. CONCLUSIONS The application of 3.5 mL of menthol was similar to the application of 0.5 kg of crushed ice in reducing peripheral blood flood. Combining crushed ice with menthol appeared to have an additive effect on reducing blood flow.
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Affiliation(s)
- Robert Topp
- Marquette University, Milwaukee, WI 53201-1881, USA.
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The effects of menthol on cold allodynia and wind-up-like pain in upper limb amputees with different levels of phantom limb pain. Neurosci Lett 2013; 534:52-7. [DOI: 10.1016/j.neulet.2012.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 10/22/2012] [Accepted: 11/05/2012] [Indexed: 12/28/2022]
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Kawasaki H, Mizuta K, Fujita T, Kumamoto E. Inhibition by menthol and its related chemicals of compound action potentials in frog sciatic nerves. Life Sci 2013; 92:359-67. [PMID: 23352972 DOI: 10.1016/j.lfs.2013.01.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 12/10/2012] [Accepted: 01/05/2013] [Indexed: 01/07/2023]
Abstract
AIMS Transient receptor potential (TRP) vanilloid-1 (TRPV1) and melastatin-8 (TRPM8) channels play a role in transmitting sensory information in primary-afferent neurons. TRPV1 agonists at high concentrations inhibit action potential conduction in the neurons and thus have a local anesthetic effect. The purpose of the present study was to know whether TRPM8 agonist menthol at high concentrations has a similar action and if so whether there is a structure-activity relationship among menthol-related chemicals. MAIN METHODS Compound action potentials (CAPs) were recorded from the frog sciatic nerve by using the air-gap method. KEY FINDINGS (-)-Menthol and (+)-menthol concentration-dependently reduced CAP peak amplitude with the IC(50) values of 1.1 and 0.93 mM, respectively. This (-)-menthol activity was resistant to non-selective TRP antagonist ruthenium red; TRPM8 agonist icilin did not affect CAPs, indicating no involvements of TRPM8 channels. p-Menthane, (+)-limonene and menthyl chloride at 7-10 mM minimally affected CAPs. On the other hand, (-)-menthone, (+)-menthone, (-)-carvone, (+)-carvone and (-)-carveol (in each of which chemicals OH or O group was added to p-menthane and limonene) and (+)-pulegone inhibited CAPs with extents similar to that of menthol. 1,8-Cineole and 1,4-cineole were less effective while thymol and carvacrol were more effective than menthol in inhibiting CAPs. SIGNIFICANCE Menthol-related chemicals inhibited CAPs and were thus suggested to exhibit local anesthetic effects comparable to those of lidocaine and cocaine as reported previously for frog CAPs. This result may provide information to develop local anesthetics on the basis of the chemical structure of menthol.
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Gao T, Hao J, Wiesenfeld-Hallin Z, Xu XJ. Activation of TRPM8 cold receptor triggers allodynia-like behavior in spinally injured rats. Scand J Pain 2013; 4:33-37. [DOI: 10.1016/j.sjpain.2012.09.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 09/24/2012] [Indexed: 10/27/2022]
Abstract
Abstract
Aims
Pain in response to innocuous cold stimulation (cold allodynia) is a common symptom in patients with neuropathic pain. Cold allodynia is difficult to treat and its mechanisms are poorly understood. Several transient receptor potential (TRP) channels have been shown to be the molecular sensors for cold stimulation in a temperature-dependent manner, but the contribution of various TRP channels in mediating cold allodynia in neuropathic pain is unclear. We have previously shown that spinally injured rats developed neuropathic pain-like behaviors, including marked cold allodynia. We now assessed the role of TRP channels in mediating cold allodynia in rats after ischemic spinal cord injury.
Methods
Methods: Spinal cord injury was produced using a photochemical method. The mechanical allodynia was assessed by examining the vocalization thresholds to graded mechanical touch/pressure applied with von Frey hairs. Temperature controlled cold stimulation was produced by a Peltier thermode (active surface 25 mm × 50 mm) connected to a MSA Thermal Simulator (Somedic, Sweden) with baseline temperature of 32 °C. The rate of temperature change was 0.5 °C/s. The temperature required to elicit cold allodynia was examined. The responses of the rats to topical application of icilin or menthol, agonists of transient receptor potential melastain 8 (TRPM8), were also studied.
Results
Normal rats did not exhibit nociceptive responses to cooling stimulation to the trunk and back area (minimal temperature +6°C) and they also did not react aversively to topical application of icilin or menthol. After spinal cord injury, the rats developed mechanical allodynia at the trunk and back just rostral to the dermatome of the injured spinal segments. In the same area, rats exhibited significant nociceptive responses to cooling from day 1 after injury, lasting for at least 70 days which is the longest time of observation. For the first two weeks after injury, the majority of spinally injured rats had a nociceptive response to cooling above 17°C. At day 70, about 50% of rats responded to cooling above 17 °C. Topical application of 400 μM icilin or 4mM menthol also elicited pain-like responses in spinally injured rats and these two cold mimetics also significantly exacerbated existing mechanical allodynia.
Conclusion
Our results showed that activation of the TRPM8 channel by menthol or icilin triggers allodynia in spinally injured rats and increases, rather than decreases, mechanical allodynia. TRPM8 channels which respond to cooling above 17 ° C may be involved at least in part in mediating cold allodynia in the rat model of neuropathic spinal cord injury pain.
Implications
The work introduced a method of quantitative testings of responses of rats to cold stimulation and may contribute to the understanding of mechanisms of cold allodynia after injury to the nervous system.
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Affiliation(s)
- Tianle Gao
- Department of Physiology and Pharmacology , Section of Integrative Pain Research , Karolinska Institutet , Stockholm , Sweden
| | - Jingxia Hao
- Department of Physiology and Pharmacology , Section of Integrative Pain Research , Karolinska Institutet , Stockholm , Sweden
| | - Zsuzsanna Wiesenfeld-Hallin
- Department of Physiology and Pharmacology , Section of Integrative Pain Research , Karolinska Institutet , Stockholm , Sweden
| | - Xiao-Jun Xu
- Department of Physiology and Pharmacology , Section of Integrative Pain Research , Karolinska Institutet , Stockholm , Sweden
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